NETDOM.exe (NT Resource Kit supplement 2, Win2K Support Tools)

Domain Manager - a whole bag of network management tools in one tool.

The syntax for NETDOM varies considerably between versions

In summary you can

  /JOINDOMAIN  /JOINWORKGROUP 
  /Add /DELETE a computer account
  (including BDC and resource domain computer accounts)
  /Query the secure channel of a resource domain or BDC
  /List the resource domain/BDCs in a domain
  /Edit trust relationships
  /Query the computer role of any domain member or BDC.

In Win2K only
  Move a workstation or member server (computer) to a new domain
  Rename/Reset a workstation or member server
  Verify or reset and synchronize TIME within a domain
  Resynchronize 'out of synch' domain controller`s 

Run NETDOM /? for full syntax - or look in the supplied WinHelp file.